Waveband Selection with Equivalent Prediction Performance for FTIR/ATR Spectroscopic Analysis of COD in Sugar Refinery Waste Water

The level of chemical oxygen demand(COD)is an important index to evaluate whether sewage meets the discharge requirements,so corresponding tests should be carried out before discharge.Fourier transform infrared spectroscopy(FTIR)and attenuated total reflectance(ATR)can detect COD in sewage effectively,which has advantages over conventional chemical analysis methods.And the selection of characteristic bands was one of the key links in the application of FTIR/ATR spectroscopy.In this work,based on the moving window partial least-squares(MWPLS)regression to select a characteristic wavelength,a method of equivalent wavelength selection was proposed combining with paired t-test equivalent concept.The results showed that the prediction effect of the selected wavelength was very close to that of the MWPLS method,while the number of wavelength points was much smaller.SEPAve,RP,Ave,SEPStd,and RP,Std which characterized the modeling effect were 26.3 mg L^-1,0.969,3.49 mg L^-1,and 0.006,respectively.The validation effect V-SEP and V-RP were 28.64 mg L^-1 and 0.960,respectively.The selected waveband was between 1809 cm^-1 and 1568 cm^-1.The method was of more reference value for the design of FTIR/ATR spectral instrument for COD detection.

Band Selection Method of Absorption Peak Perturbance for the FTIR/ATR SpectrumAnalysis

The rapid quantification method of human serum glucose was established by using the Fourier transform infrared spectroscopy(FTIR)and attenuated total reflection(ATR).By the subtracted spectra between glucose aqueous solution and de-ionized water,absorption peaks are calculated in fingerprint area.Based on these absorption peaks and multiple linear regression(MLR)model,discrete band selection method of absorption peaks disturbance model(APDM)was developed.5 absorption peaks 1150 cm^-1,1103 cm^-1,1078 cm^-1,1034 cm^-1,991 cm^-1 were found in fingerprint area.Used these absorption peaks to establish absorption peaks disturbance model,the optimal wavelength combinations are 1140 cm^-1,1096 cm^-1,1084 cm^-1,1030 cm^-1,993 cm^-1,the corresponding C-RMSEP and C-RP are 1.164 mmol/L and 0.828 respectively.The results show that the optimal prediction effect of APDM was obviously better than the one of the Partial least squares(PLS)model,and the complexity of the optimal model is reduced greatly also.The results also provide a theoretical basis for design of small and portable human serum glucose spectrometer.